I have seen it referred to both ways, so it can be a bit confusing. Generally in recipes it seems like people refer to it as a part of percentage of the total dough weight, but on this very interesting thread at pizzamaking.com: http://www.pizzamaking.com/forum/index.php?topic=22649.0 they have a predictive model chart for starter in dough that uses the amount of starter as a percentage of the total flour in the recipe.

The way I interpret that paper is, they treat the sponge as a separate ingredient (they give the recipe for the sponge). Once made up, the amount of sponge used in the dough is 20% of the flour weight of the dough, i.e. 100 g flour and 20 g of the finished sponge.

In calculating baker's percentages you never use the final dough weight in the calculations. The final dough weight would include the weight of the flour, water, salt, other ingredients (sugar,), etc.. You wouldn't use sugar in sourdough but you would in a cake recipe. All of the ingredients are based on the flour weight which is normalized to 100.

In a bakery using 100 lbs. of flour (two 50-pound sacks), the "other" sourdough recipe would use 20 pounds of finished sponge, 60 pounds of water (about 7 gallons) and 2 pounds of salt. It adds up when baking on a large scale.

The percentages used in baker's percentage are the percent of the flour weight, which is always 100%.

THANK YOU and that's what I wanted to hear. Here's an example of my math:

500g flour (excluding flour contained in the levain). Therefore...200g levain (this is the 40% levain at 100% hydration)350g water (this is the 70% hydration based on the wt of flour listed above)------------------------1050g dough==============

The dough, therefore consists of:600g flour TOTAL450g water TOTAL and so this represents 75% hydration instead of 70% as shown above. The calculation of hydration is the source of my confusion:

1) HYDRATION that is based on ADDED FLOUR exclusive of the flour in the levain;

2) HYDRATION that is based on the GRAND TOTAL OF FLOUR in the dough: that is, the flour in the levain + added flour.

I do, indeed, hope that I've clarified this math and my confusion. Upper case added for emphasis and clarity. 8)

I find this confusing as well. 20% of either flour or total dough weight is definitely a significant enough quantity to change the hydration level in the recipe, unless of course one is careful to build the levain at the same hydration percentage one desires in the finished dough.

When I forumlate a bread from scratch, I calculate what percentage of total flour weight should be in the preferment, for sourdough I keep it between 10-20% depending on how quickly I want the dough to rise, if I'm going to be bulk fermenting, and how sour I want the final bread. From that percentage, I figure out how much starter to use, depending on the hydration of the starter. Examples for 500g total flour:

Both of these breads have the same basic formula, but with a different percentage of pre-fermented flour. The confusion comes in when you say "40% starter" if we are talking bakers percentage, that works out to a totally different number using different methods.

The problem I have with this method, is that it does not count the water in the starter into the hydration %, nor the flour for calculating salt% So on the face of it the bread looks balanced, however if you crunch the numbers on that last bread, you get this:

hydration: 75%salt: 1.6%prefermented flour: 16.6% total flour weight

The hydration percentages and salt percentages aren't completely visible right away, and a 75% hydration dough behaves much differently than a 70% hydration dough, like one might be expecting when reading the above formula, the salt content is also a bit low. This descrepancy is the main beef i have with the Dan Leader book "Local Breads," as he does not count the starter in his hydration calculation (Chad Robertson is guilty of this as well). This may seem easy to remedy with a 100% hydration starter, but it becomes much more difficult if you have a 50% 60% or 130% starter, like are called for in the Leader book.

Soooo the "to long didn't read" version: I think it's better to calculate the raw bread formula first, with the total flour/water/salt/enrichments, find the amount of pre-fermented flour you want, then subtract thoes amounts from your raw formula.

I am currently undergoing training to be a Bread Baker's Guild of America (BBGA) formula formatter, so forgive me for being a bit - um - "rigid."

Please go to www.bbga.org and you will find (in the public area) standards for writing formulas.

In this thread, mixinator (method 2) and baybakin (showing us the "right way") come closest to the BBGA standards.

We seem to have these same discussions over and over. Although "rigid" the BBGA standard is simple, straightforward and works every time for every formula you can imagine. I know that knuckling under and using a standard method may take the fun out of the process for some folks, but weighed against the flexibility and understanding that a standard method brings - well, the standard makes things so much better. One question I have often seen posted is :How do I convert from commercial yeast to sourdough? can have a complex answer, but using the BBGA standard is a trivial problem.

I get distracted when authors use other standards, but even then, you should be able to take their base formulas and convert them. "40% starter" tells me nothing by itself, but with additional information can be made to fit the standard.

It is well worth even the home baker's time to learn this method. Once learned, instead of being restrictive, the BBGA standard is actually quite freeing.

I'm going to end this sermon - but really, the BBGA website is worth a look.

I plan to follow the layout and process as indicated in those charts. They clarify things better than I could.

The one comment I'll make applies to PART II DIAGRAM 1. The individual weight of flour and water contained by the "seed" do not figure into flour and water totals for Final Dough; and, do not figure into the flour and water totals for the Total Dough Weight.

In essence, the actual breakdown of the flour and water seed is not done. The seed is considered a unit unto itself and its actual flour and water contribution is negligible, shall we say.

elsewhere, the discounting of the amount of flour and water in the seed is a simplifying assumption, and yes, as you say, because it is usually a small amount in relation to the dough and since the process of bread making itself has plenty of variation, one that causes no harm.

Because I like to do algebra, I actually did make up a spreadsheet that took the hydration of the seed into account. Interesting mathematically, but for baking, not really worth it.

I agree with Bob Marley, though, about the example in Part II, Diagram 1 - they didn't go the extra step and break out the composition of the seed. It's a small amount in terms of the finished recipe, of course, but it's a large enough amount to change the hydration of the preferment quite a bit. If the seed in that example is at 100% hydration, the final preferment hydration will be 58.1%. However, if the seed is at 50% hydration, the final preferment will be 55.5% hydration - not a huge difference, but enough that you might want to account for it in your formulation.

Note also, the small amount of seed usually used. The seed is taken from a storage starter to create the pre ferment.

These standards were developed with the input of a number of respected professional bakers and are, indeed,evolving, but they are intended for practical applications, not particularly for mathematical interest.

Since we start with the overall formula and determine the hydration there, the control is in the final dough. In the final mix the baker will still add water if he/she thinks the dough needs it thereby changing the actual hydration from the theoretical hydration in the formula.

Same with the pre ferment. If, when it is mixed, it "seems" too dry, the baker will add more water regardless of what the formula tells her/him.

There are two factors - the mathematical interest and the very variable process due to variable ingredients, and frankly, the dough being a living creature. You don't over calculate when the process doesn't support it (and we have been presented with this in the context of our training. It's engineering vs. pure science.)

the interesting things about TFL is the high number of folks (like myself) who come from the "high burnout" professions like software and various branches of engineering. We've got that mathematical precision drive and the math background that makes some of these calculations sort of trivial.

Although I have met professional bakers with great math skills, the majority of them have their primary talents in other areas and instead of loading on theory, the math is kept to what is useful. I have personally wilted a bit when methods for scaling formulas up and down have been discussed, since what is done through various "factors" seems more straightforward with a little algebra. I like algebra, but a lot of people don't really get it. So when we say to bakers - even when teaching this to them - "we do not need to account for the hydration of the seed," we get nods of comprehension and (sometimes) gratitude.

If I were teaching this to a room full of engineers, I would have in my back pocket a spreadsheet that would show how theoretically the hydration of the seed impacts the entire process. I do have that spreadsheet, and I abandoned it because it really wasn't more useful than the standard.

I'm not trying to pile on, but as welcoming as the BBGA is to home bakers, it is primarily geared for the professional baker. I am currently working on a translating a formula from what would seem to most people to be a pretty complete recipe into BBGA format. Frankly its challenging enough - even with my Excel skills, engineering degree, and years of complex software validation - that I'm kind of grateful for any simplification I can get.

Sorry to go on and on, but I am immersed in this right now. It is harder to write a formula for publication than one might think.

because on this thread we've spoken about standards and attention to detail.

I just finished formatting a formula (in the BBGA format) for a simple bread with a pre ferment and a soaker. It started with a recipe as most bakers would dash them off.

I was thinking "How hard can this be?"

Well, after 4 hours, I managed to get it formatted along with all the assumptions I had to make to put it in that format. It was non-trivial.

I am gaining a lot of respect for people who write books (if they are well written, that is). The format (not just the spreadsheet of percentages) is a very good tool to make the baker think about what he/she really did.

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